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@eslint/plugin-kit is vulnerable to Regular Expression Denial of Service attacks through ConfigCommentParserGHSA-xffm-g5w8-qvg7

Fix: eslint/rewrite@b283f64

GHSA-xffm-g5w8-qvg7 is a security vulnerability in @eslint/plugin-kit. A fix is available for @eslint/plugin-kit — see the affected versions and patch details below.

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 10, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

45other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
@eslint/plugin-kitnpm
78.3Mdownloads / week

Description

Summary

The ConfigCommentParser#parseJSONLikeConfig API is vulnerable to a Regular Expression Denial of Service (ReDoS) attack in its only argument.

Details

The regular expression at packages/plugin-kit/src/config-comment-parser.js:158 is vulnerable to a quadratic runtime attack because the grouped expression is not anchored. This can be solved by prepending the regular expression with [^-a-zA-Z0-9/].

PoC

const { ConfigCommentParser } = require("@eslint/plugin-kit");

const str = `${"A".repeat(1000000)}?: 1 B: 2`;

console.log("start")
var parser = new ConfigCommentParser();
console.log(parser.parseJSONLikeConfig(str));
console.log("end")

// run `npm i @eslint/[email protected]` and `node attack.js`
// then the program will stuck forever with high CPU usage

Impact

This is a Regular Expression Denial of Service attack which may lead to blocking execution and high CPU usage.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npm@eslint/plugin-kitall versions0.3.4npm install @eslint/plugin-kit@0.3.4

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @eslint/plugin-kit, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update @eslint/plugin-kit to 0.3.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xffm-g5w8-qvg7 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Summary The `ConfigCommentParser#parseJSONLikeConfig` API is vulnerable to a Regular Expression Denial of Service (ReDoS) attack in its only argument. ### Details The regular expression at [packages/plugin-kit/src/config-comment-parser.js:158](https://github.com/eslint/rewrite/blob/bd4bf23c59f0e4886df671cdebd5abaeb1e0d916/packages/plugin-kit/src/config-comment-parser.js#L158) is vulnerable to a quadratic runtime attack because the grouped expression is not anchored. This can be solved by prepending the regular expression with `[^-a-zA-Z0-9/]`. ### PoC ```javascript const { ConfigComme
O3 Security · Impact-Aware SCA

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@eslint/plugin-kit is vulnerable to Regular Expression…